Almost all the time until the superior levels had passed. The trio was still exhausted. They felt like those fifteen minutes had been only two.
Casper was the only one used to get short times of rest for great amounts of effort, so fifteen minutes for him were quite a lot, although he couldn't ignore the limits of his body and make it be 100% recovered just in this short period of rest.
The soldier was the first one to stand up and get prepared. He was not sure if there would be enemies waiting for the elevator to come, so he needed to be ready for a fight if needed.
The other two got the cue and raised from the ground as well, looking pretty unpleased to be moving again so early, but determined to finish it as soon as possible.
Casper was anxious for that elevator to arrive. Once they got into the superior levels, they would need just a bit more struggle and then they would be already in the outside world again.